“In a deep sense, the actions of Boko Haram represent the complete antithesis of the values inherent in education,” Lagarde told a gathering of women leaders at the National Democratic Institute in Washington.

“For their action degrades the dignity of the human being, while education uplifts, enflames, and ennobles the human spirit,” she said.

“This is why groups like Boko Haram in Nigeria, who kidnap and sell into slavery young girls who simply want to go to school, are despicable - they themselves should be found and forced to go to school for life.”

Lagarde joined the global call to free the girls, who were snatched from their school at gunpoint more than a month ago.

“Let us join our voices to the voices of the world, and let loose an impassioned plea: bring back our girls, bring back our girls. Respect our girls,” she said.

The extremist Islamist group has faced global condemnation for the abduction in the remote north-eastern town of Chibok.

Several countries including the United States, France and Britain have offered help to find them. - Sapa-AFP